Electrical condenser



y 1935- P. J. PACKMAN 2,001,153

ELECTRICAL comasnsnn Filed Aug. 12, 19:51 2 SheetsSheet 1 May 14, 1935. P. J. PACKMAN ELECTRICAL CONDENSER Filed Aug. 12, 1931 2 Sheets-Sheet 2 Patented May 14, 1935 UNITED STATES PATENT OFFICE ELECTRICAL CONDENSER Application August 12, 1931, Serial No. 556,481

In Great Britain April 2, 1931 3 Claims.

This invention relates to electrical condensers and especially to condensers of the moving vane yn The principal object of the invention is to pro- 5 vide an improved method of connecting the vanes of an electrical condenser to a support for bolding them in their proper spaced relation to one another. The. invention has in mind more particularly the demands or manufacture on mass production lines.

Hithereto it has been cutomary to solder the vanes to the support. In an alternative method, the support has taken the form of a thick walled tube which is received in notches in the edge of the vanes. The tube is saw-cut to receive the edges of the notches, and after the vanes have been assembled with the tube in place by means of an appropriate jig, a stagging tool is applied to the outside of the tube between the saw-cuts therein, which tool has the effect of spreading the metal of the tube between the saw-cuts into firm engagement with the condenser vanes, so that the latter become held in the cuts and thereby fixed to the tube.

These, and other methods are all somewhat costly and time-consuming operations, especially from the point of view of mass production. Moreover, they are frequently ineffective. Even when the greatest care is taken it is often experienced 30 that one or more of the condenser vanes is a little loose and this, as is known in the art, is most undesirable, for accuracy of spacing of the vanes in an electrical condenser is of the utmost importance, more especially in the case of moving- 35 vane type condensers for use in ganged arrangement in wireless apparatus. Furthermore, the

production of a soldered connection is generally a somewhat dirty operation and undesirable from this point of view.

The present invention comprises an electrical condenser of the type having a supporting member extending through apertures in the vanes to hold them in spaced relation to one another, characterized in that the supporting member is provided with a jamming surface to be forced into jamming engagement with said apertures by a relative movement between it and the vanes.

The apertures in the varies and the cross section of the supporting member may be of such 50 non-circularcontour that the supporting member may be jammed into engagement with the vanes by relative movement with respect thereto about its longitudinal axis.

Preferably, the apertures in the vanes and the cross-section of the supporting member are of simlar volute contour, the supporting member being first inserted into the apertures in the vanes with its volute section coinciding with the volute contour of the said apertures, and then turned about its longitudinal axis to jam it into engagement 5 with the vanes.

The vanes of the condenser may be assembled at their desired spacing by means of temporary spacers interposed between them. These spacers may take the form of loose elements, for example, 10 loose plates cut to the shape of the condenser vanes. In this case, the operator would build up on a suitable assembly jig a pack composed ofcondenser vanes alternated in alignment with one another with spacer plates. Alternatively, 15 the spacers may be connected together as a unit forming part of the assembly jig for the vanes, in which case, the operator would simply insert the vanes between the spacers, manipulating them in the jig to their proper positions of alignment with one another. In order that the invention may be more readily understood a specific example thereof will now be described with reference to the accompanying drawings in which Figure l is an elevation of a gang condenser in accordance with the invention,

Figure 2 is a plan view of Figure 1,

Figure 3 is a section on the line 3'3 of Figure 1, v

Figure 4 is a perspective view showing the method of assembly of the moving vanes, and

Figure 5 is a perspective view showing the method of assembly-of the fixed vanes.

Like reference numerals indicate like parts throughout the drawings.

In Figures 1 and 2 a 3-unit gang condenser is shown in which for simplicity the fixed vanes are omitted from the central unit and the moving vanes are omitted from the right-hand unit. The condenser is built up on a sheet metal frame It) having ends H and partitions ID. The spindle I! of the moving vanes is carried in bearings in the ends I I and passes freely through large apertures in the partitions l8. The moving vanes I6 are stamped from sheet metal with apertures of volute contour as shown in Figure 3 and are assembled in a manner to be described hereafter on the spindle I 1 which consists of an extruded brass rod of similar volute section. A stay member 40 also of volute contour passes through apertures of volute contour near the tips of each set of moving vanes and is held in position by jamming in a similar manner. 5

The fixed vanes l2 are also formed with apertures of volute contour through which pass supporting members 13 of volute cross section. The supporting members also pass through volute apertures in brackets 14, the supporting members l3 being simultaneously secured to the fixed vanes and the brackets by a jamming movement. The brackets I4 are screwed to insulating plates l5 riveted to the frame of the condenser. The insulating plates carry connecting lugs and terminals 4i and 42 respectively.

The method of assembling the moving vanes on their supporting spindle is shown in Figure 4.-

Each set of vanes is inserted in a cradle 45 of which in this case there are four for a 4-unit gang condenser and which has an exterior surface of substantially semi-cylindrical form coaxial with the centres of the holes through the vanes. The cradles 45 are carried in a guide member 46 which has semi-circular grooves 41 to co-operate with corresponding ribs 48 on the cradles. The latter can therefore be rocked about the axis of the holes through the vanes. Each cradle is provided with a locking plate 49 to bear upon the edges of the vanes and a link 50 and lever 51 by which the cradle can be rocked about the axis of the holes in the vanes. When all the vanes have been assembled in the cradles the spindle is inserted through the holes in them.

The supporting member may conveniently take the form of a solid extruded-rod of the required volute section. Such rod is readily and cheaply obtainable, and as will be appreciated by those acquainted with the manufacture of condensers more especially for wireless apparatus, the employment of a solid rod as referred to eliminates the necessity usual with tubular vane hubs of threading a solid rod or core through the tubular hub and fixing it in place therein by means of collars on the tubular hub and grub screws; the solid rod used in the method according to the invention is simply turned down where required to fit the framework bearings of the condenser.

To grip the spindle a clamping means is provided comprising a fixed bracket 52 in which are pivoted two arms 53 connected by a bridge member 54 from which depend five clamping arms 55. Each clamping arm 55 has secured to it a pair of triangular plates 56 between which a clamping lever 51 is pivoted. The lower end of the clamping lever 51 forms a jaw to co-operate with the lower end of the clamping arm 55 to grip the spindle and the upper end of the clamping lever 51 is provided with a fork within which is pivoted a bell-crank of which one arm constitutes a cam 58 and the other arm a handle 59. The jaws afforded by the lower ends of the clamping arm and clamping lever are provided with rounded recesses to embrace the spindle. The recesses, however, are not cylindrical but lie on a volute curve of which the smallest radius corresponds with a point on the face of the clamping arm 55 whereby this face affords a shoulder 60 to prevent rotation of the spindle. By raising the handles 59 the clamping jaws are brought firmly together and the action of the shoulder 60 is assisted by the friction between the jaws. The spindle having been clamped the levers 5| are now moved to the position in which one of them (the second from the right) is shown thereby securely jamming the vanes into fixed relationship with the spindle. It will be seen that the spindle is gripped at five points spaced along its length and therefore objectionable twisting of the spindle about its axis with inequality of alignment of the various sets of vanes is avoided.

tion, the cradles then rocked to lock the vanes to the spindle and the cradles then rocked back again leaving the vanes partly outside them. The arms 53 are then raised to withdraw the assembled moving vanes from the jig. The use of the arms for the latter purpose prevents any chance of bending or jamming the vanes during removal.

The fixed vanes are assembled in a similar manner to the moving vanes, being mounted in a jig of suitable form together with the brackets I4. The supporting members are then inserted through the apertures and a tool 62 similar to the tool SI is employed to twist the supporting members to fix them securely to the vanes and the brackets. The arrangement of the fixed vanes is shown diagrammatically in Figure 5.

In a modified arrangement all the vanes both fixed and moving are assembled together in a jig in the spaced relationship they will ultimately occupy in order to ensure that the spacing between neighbouring plates is uniform.

In general it is found that comparatively small angular movement is sufiicient to secure the vanes to their supporting members but for the sake of safety a movement of some 60 is preferably employed. Under these circumstances the material of the vanes is strained and all the vanes are equally firmly secured to the spindle.

The thickness of the sheet material from which condenser vanes are made as ordinarily obtainable, generally varies from the correct gaugethickness within the limits of .0005" thicker to .0005" thinner. To allow for this manufacturing margin and prevent it from incurring an accumulation of error in the spacing of the vanes, the spacers employed in the assembly of the vanes may be supported in positions such that the distance between the opposing faces of adjacent spacers slightly exceeds, e. g. by .0005" the gaugethickness of the sheet material from which the condenser vanes are made.

This may be accomplished in any convenient manner. If the spacers take the form of loose plates, the plates may be provided with thickened palm-portions lying clear of the contour of the vanes to be inserted between the plates, and of such a thickness, that if the plates are clamped together palm-portion to palm-portion, the width of spaces between the plates exceed the gauge-thickness of the condenser vane material by the manufacturing margin to be allowed. As will be appreciated, in this case, a pack of spacer plates is first assembled and clamped together palm-portion to palm-portion after which the condenser vanes are inserted in the spaces between the plates, and if the actual thickness of the vane material should be slightly greater or slightly less than the gauge-thickness, this error will not be cumulative in the spacing of the vanes.

Similarly, in the case of the spacers being an integral part of an assembly jig for the vanes, in contrast to their taking the form of loose plates,- which can be assembled in a pack as above described, the spacer elements are spaced apart the requisite distance to allow for the manufacturing margin in the thickness of the vane material.

As will be understood when employing a supporting member of volute section and correspondingly shaped volute apertures to receive it in the vanes, a short portion of the circumference of the aperture is unsupported by contact with the supporting member. Usually, in the case of the moving vanes, the vane hub is positioned near one edge of the vane, and where this is the case, it is preferred to arrange that the aforesaid unsupported part of the contour of the vane apertures shall be situated on that side of the aperture which is remote from the body of the vanes as shown in Figure 3. This arrangement is desirable in,view of the importance of securing rigidity of connection as between vanes and the supporting member.

A similar arrangement may be employed in the case of the stay member for the tips of the moving vanes and also in the case of the frame rods for the fixed vanes.

In order to distribute the unsupported part of the contour of the vane apertures, the said contour and that of the section of the supporting member may comprise a plurality of volutes.

The advantages of the invention are various. The principal advantage is the extreme simplicity and ease of the operations involved making for a marked lessening of the cost of manufacture of condensers, more particularly in mass production.

A further advantage is that the connection between the vanes and the supporting member is uniformly firm for every vane along the member.

Another advantage is that the vanes are not subjected to forces tending to distort them out of their true theoretical plane. The forces which are applied to the parts are transmitted to the vanes in the plane of the vane and consequently the permanent reaction forces in the vane due to the elasticity of the material, while serving to secure the vanes firmly to the supporting member, are exercised in the plane of the vane only .and, therefore, in directions in which they cannot set up distortion of the vane.

I claim:-

1. An electrical condenser comprising the combination of a plurality of vanes having apertures therein of volute cross-section and arranged in any desired spaced relationship and a vane supporting member of similar volute cross-section supporting member is passed through the said apertures and is jammed against the walls of the apertures to support the vanes in spaced relation.

3. An electrical condenser comprising the combination of a plurality of vanes having apertures therein of non-circular cross-section and spaced apart to any desired degree, a fixing bracket also formed with apertures of similar non-circular cross-section, and a vane supporting member which is of uniform cross-section throughout its vane supporting length and which is of substantially the same cross-sectional form as the said apertures, which supporting member passes through the said apertures in said vanes and said fixing bracket, and is jammed against the walls of the apertures to support the vanes in spaced relation.

PERCIVAL JAMES PACKMAN. 

